The effect of land-use disturbance on the physiological stress response of creek chub at multiple scales

It is critical for fisheries ecologists to evaluate physiological responses to understand how fish cope with anthropogenic disturbances that have the potential to cause population declines.  Few studies have quantified the underlying physiological mechanisms that dictate the ability of fish to cope with human disturbance.  The purpose of this study was to quantify the influence of watershed and segment-scale land-use disturbance on the physiological responses of stream fish.  To test this, Creek chub were collected from replicated agricultural (disturbed) and forested (control) streams and subjected to heat and hypoxia stressors to evaluate blood and whole animal physiological responses.  No differences in baseline physiological parameters were found in fish sampled immediately from streams within forested or agricultural streams at either scale.  However, when exposed to low oxygen conditions in the lab, creek chubs from forested watersheds had a higher stress response and greater ion loss than fish from agricultural watersheds.  Furthermore, creek chubs from forested watersheds and segments had higher metabolic rates than agricultural site fish when exposed to high temperatures in the lab. These results indicate that fish from disturbed streams may not have the resources to produce a strong stress response making them vulnerable to future degradation.